Gophersnake - Pituophis catenifer
Pituophis catenifer sayi
(see State Rank Reason below)
State Rank Reason (see State Rank above)
Species is relatively common within suitable habitat and widely distributed across portions of the state
- Details on Status Ranking and Review
Gophersnake (Pituophis catenifer) Conservation Status Review
Review Date = 05/03/2018
ScoreG - 200,000-2,500,000 km squared (about 80,000-1,000,000 square miles)
Comment380,531 square Kilometers from Natural Heritage Program range maps
ScoreE - Relatively Stable (±25% change)
CommentHabitat is likely stable within +/- 25% since European settlement, but persecution by people may drive local extirpations of this species
ScoreU - Unknown. Short-term trend in population, range, area occupied, and number and condition of occurrences unknown.
CommentNo data on trends available
ScoreH - Unthreatened. Threats if any, when considered in comparison with natural fluctuation and change, are minimal or very localized, not leading to significant loss or degradation of populations or area even over a few decades’ time. (Severity, scope, and/or immediacy of threat considered Insignificant.)
CommentUnknown, but mortality due to basking on roads both directly from vehicle collisions and persecution due to increased visibility may contribute to higher mortality of reproductive aged individuals.
ScoreB - Moderately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance over a period of several years (on the order of 5-20 years or 2-5 generations); or species has moderate dispersal capability such that extirpated populations generally become reestablished through natural recolonization (unaided by humans).
CommentModerately Vulnerable. Species exhibits moderate age of maturity, frequency of reproduction, and/or fecundity such that populations generally tend to recover from decreases in abundance within 5-20 years or 2-5 generations. Species has good dispersal ca
ScoreC - Moderate. Generalist. Broad-scale or diverse (general) habitat(s) or other abiotic and/or biotic factors are used or required by the species but some key requirements are scarce in the generalized range of the species within the area of interest.
CommentWithin its range this species is associated with a wide range of habitats
Raw Conservation Status Score
3.5 + 0 (geographic distribution) + 0 (environmental specificity) + 0 (long-term trend) + 1 (threats) = 4.5
The Gophersnake or Bullsnake is Montana’s largest snake and can reach a length of 7 feet; most range in length from 3 to 5 feet. It can be readily identified by a series of large black to brown blotches that run down the back, and another series along the sides. The blotches, which are set on a yellow background, become more widely spaced toward the tail. The dorsal scales are keeled (have a ridge running down the center). A black band can usually be seen on the head in front of and extending below the eyes. The belly is yellow to white, often spotted with black. Dorsal coloration varies geographically, but in most areas has numerous dark blotches on a cream or yellowish background.
Differs from other similar species by having the following combination of characteristics: keeled scales, 4 prefrontals, and an undivided anal plate. Rat snakes (Elaphe) and kingsnakes (Lampropeltis), have only two prefrontal scales. Also, Elaphe has a divided anal plate. Whipsnakes (Masticophis), racers (Coluber), and indigo snakes (Drymarchon) have smooth body scales.
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Gophersnakes are associated with dry habitats, including open pine forests. They feed on rodents, rabbits, ground-dwelling birds, and to a lesser extent lizards. They sometimes hiss and vibrate their tail when alarmed, producing a sound similar to that of rattlesnakes. They occasionally climb trees. Females lay 2 to 24 eggs in summer. North-central MT: of 12 records, 9 in river valley, 1 in coulee, 2 on prairie (Mosimann and Rabb 1952). One found in rocky sagebrush area north of Arlee, MT (Franz 1971). Common in southeast Alberta in brushy coulees, sage flats, and along roads (Lewin 1963).
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: mtnhp.org/requests
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Human Land Use
Recently Disturbed or Modified
Shrubland, Steppe and Savanna Systems
Sparse and Barren Systems
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Human Land Use
Recently Disturbed or Modified
Wetland and Riparian Systems
Active forager by searching.
Overwinter survival in northern UT greater than 88% (adults), 25% (juveniles) (Parker and Brown 1980). Densities of 1.3 snakes/ha reported for ID (Nussbaum et al. 1983).
Mate in late May to June; lay eggs late June to July; hatch late August to September (Hammerson 1982). Clutch size averages 12.4 (Fitch 1970). Hatching success in northern Utah was 92% (Parker and Brown 1980).
- Literature Cited AboveLegend: View Online Publication
- Fitch, H.S. 1970. Reproductive cycles of lizards and snakes. University of Kansas. Museum Natural History Miscellaneous Publication 52:1-247.
- Franz, R. 1971. Notes on the distribution and ecology of the herpetofauna of northwestern Montana. Bulletin of the Maryland Herpetological Society 7: 1-10.
- Hammerson, G.A. 1982. Amphibians and reptiles in Colorado. Colorado Division of Wildlife. Denver, CO. 131 pp.
- Lewin, V. 1963. The herpetofauna of southeastern Alberta. Can. Field-Nat. 77:203-214.
- Mosimann, J.E. and G.B. Rabb. 1952. The herpetology of Tiber Reservoir Area, Montana. Copeia(1): 23-27.
- Nussbaum, R.A., E.D. Brodie, Jr. and R.M. Storm. 1983. Amphibians and reptiles of the Pacific Northwest. University of Idaho Press. Moscow, ID. 332 pp.
- Parker, W.S. and W.S. Brown. 1980. Comparative ecology of two Colubrid snakes, Masticophis t. taeniatus and Pituophis melanoleucus deserticola, in northern Utah. Milwauke Public Museum Publishers Biology Geology 7: 104p.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- [DCC] Decker Coal Company. 1998. 1997 Consolidated annual progress report. Decker Coal Company West, North and East Pits. Decker, MT.
- [EI] Econ Incorporated. 1984. Terrestrial wildlife inventory for the Lame Jones and Ismay coal lease tracts. Econ Incorporated. Helena, MT.
- [OEA] Olson Elliot and Associates Research. 1985. 1983-1984 Wildlife monitoring report for the CX Ranch project. Olson Elliot and Associates Research. Helena, MT.
- [PRESI] Powder River Eagle Studies Incorporated. 1998a. Big Sky Mine 1997 wildlife monitoring studies. Powder River Eagle Studies Incorporated. Gillete, WY.
- [PRESI] Powder River Eagle Studies Incorporated. 1998b. Spring Creek Mine 1997 wildlife monitoring studies. Powder River Eagle Studies Incorporated. Gillete, WY.
- [VTNWI] VTN Wyoming Incorporated. No Date. Second year's analysis of terrestrial wildlife on proposed mine access and railroad routes in southern Montana and northern Wyoming, March 1979 - February 1980. VTN Wyoming Incorporated. Sheridan, WY. 62 p.
- [WESCO] Western Ecological Services Company. 1983a. Wildlife inventory of the Knowlton known recoverable coal resource area, Montana. Western Ecological Services Company, Novato, CA. 107 p.
- [WESCO] Western Ecological Services Company. 1983b. Wildlife inventory of the Southwest Circle known recoverable coal resource area, Montana. Western Ecological Services Company, Novato, CA. 131 p.
- [WESTECH] Western Technology and Engineering Incorporated. 1993. Diamond Hill Project Wildlife Baseline Survey. Western Technology and Engineering, Inc., Helena, Mt.
- [WESTECH] Western Technology and Engineering Incorporated. 1998. Wildlife Monitoring Absaloka Mine Area 1997. Western Technology and Engineering, Inc., Helena, Mt.
- Allen, J. A. 1874. Notes on the natural history of portions of Dakota and Montana Territories, being the substance of a report to the Secretary of War on the collections made by the North Pacific Railroad Expedition of 1873. Proceedings of the Boston Society of Natural History. pp. 68-70.
- Allen, R. 1996. Profile of the bull snake. Rephiberary 222: 11-12.
- Amstrup, S. C., and T. P. McEneaney. 1980. Bull snake kills and attempts to eat Long-eared Owl nestlings. Wilson Bulletin 92(3):402.
- Arnold, M.L. 1929. Bull snakes do bite! Yellowstone Nature Notes 6(9): 6.
- Atkinson, E.C. and M.L. Atkinson. 2004. Amphibian and reptile survey of the Ashland and Sioux of the Custer National Forest with special emphasis on the Three-Mile Stewardship Area:2002. Marmot's Edge Conservation. 22 p.
- Bartley, G.R. 1996. Successful breeding of: Pituophis melanoleucus affinis. Herptological Review 21(2): 61-66.
- Bauer, D. 1997. 1997 wildlife study Savage Mine report. Knife River Corporation, Savage Mine. Richland County, MT.
- Bauer, Delane, 2002, 2002 Four Seasons Wildlife Study. Savage Mine Report, Richland County, Montana.
- Bauerle, B.Allen. 1972. Biological productivity of snakes of the Pawnee site. D.A. Thesis, University of Northern Colorado; 86p. 1972.
- Baxter, G.T. and M.D. Stone. 1985. Amphibians and reptiles of Wyoming. Second edition. Wyoming Game and Fish Department. Cheyenne, WY. 137 p.
- Beasom, S.L. and O.H. Pattee. 1975. An encounter between a turkey and a Bullsnake. Wilson Bulletin 87(2): 281-282.
- Bechtel, E.R. and T. Whitecar. 1983. Genetics of striping in the gopher snake, Pituophis melanoleucus. Journal of Herpetology 17(4): 362-370.
- Bechtel, H.B., J.W. Nelson, and E. Bechtel. 1980. Histochemnical demonstration of two types of albinism in San Diego gopher snakes (Pituophis melanoleucus annectens) by use of dopa reaction. Copeia 1980(4): 932-935.
- Bergeron, D. 1978. Terrestrial Wildlife Survey Coal creek Mine Area, Montana. Unpublished report for Coal Creek Mining Co., Ashland, Montana.
- Bergeron, D.J. 1978a. Terrestrial wildlife survey Divide Mine area, Montana 1977-1978. Western Technology and Engineering, Inc. Helena, MT.
- Bergeron, D.J. 1978b. Terrestrial wildlife survey P-M Mine area, Montana 1977-1978. Western Technology and Engineering, Inc. Helena, MT.
- Best, L.B. 1977. Bullsnake preys on rough-winged swallow nest. Condor 79(4): 509.
- Blatchford, D. 1990. The effect of different incubation temperatures on bullsnakes (Pituophis melanoleucus) behaviour and physiology.]. Nordisk Herpetologisk Forening 33(6): 173-177.
- Bledsoe, B.W. 1979. Life cycle of Sarcocystis sp. in deer mice and gopher snakes. Ph.D. Dissertation, University of Illinois (Urbana-Champaign); 145p. 1979.
- BLM. 1982b. Moorhead baseline inventory - wildlife. Bureau of Land Management, Miles City District Office. Miles City, MT. 29 pp.
- Boundy, J. 2001. Herpetofaunal surveys in the Clark Fork Valley region, Montana. Herpetological Natural History 8: 15-26.
- Boundy, J. and J.P. O’Brien. 1988. A longevity record for a colubrid snake. Bulletin of the Chicago Herpetological Society 23(7): 107.
- Boundy, J. and T.G. Balgooyen. 1988. Record lengths for some amphibians and reptiles from the western United States. Herpetological Review 19(2): 26-27.
- Bramblett, R.G., and A.V. Zale. 2002. Montana Prairie Riparian Native Species Report. Montana Cooperative Fishery Research Unit, Montana State University - Bozeman.
- Brown, W.S. and W.S. Parker. 1982. Niche dimensions and resource partitioning in a great basin desert snake community. U.S. Fish and Wildlife Service Wildlife Resources Rep.; 13: 59-81.
- Brunson, R.B. 1955. Check list of the amphibians and reptiles of Montana. Proceedings of the Montana Academy of Sciences 15: 27-29.
- Bryson, R.W., Jr. 2006. Pituophis catenifer (gopher snake) diet. Herpetological Review 37(1):95.
- Bullock, R.E. 1981. Tree climbing bullsnakes. Blue Jay 39(3): 139-140.
- Bureau of Indian Affairs, Department of the Interior. 1981. Draft Environmental Impact Statement. Unpublished report for the Crow/Shell Coal Lease, Crow Indian Reservation, Montana.
- Burger, J. 1989a. Following of conspecific and avoidance of predator chemical cues by pine snakes (Pituophis melanoleucus). Journal of Chemical Ecology 15(3): 799-806.
- Burger, J. 1989b. Incubation temperature has long-term effects on behaviour of young pine snakes (Pituophis melanoleucus). Behavioral Ecology and Sociobiology 24(4): 201-207.
- Burger, J. 1991a. Effects of incubation temperature on behavior of hatchling pine snakes: Implications for reptilian distribution. Behavioral Ecology and Sociobiology 28(4): 297-303.
- Burger, J. 1991b. Response to prey chemical cues by hatchling pine snakes (Pituophis melanoleucus): effects of incubation temperature and experience. Journal of Chemical Ecology 17(6): 1069-1078.
- Burger, J. 1992. Trace element levels in pine snake hatchlings: tissue and temporal differences. Archives of Environmental Contamination and Toxicology 22(2): 209-213.
- Burger, J. and M. Gochfeld. 1985. Behavioural development: nest emergence of young pine snakes (Pituophis melanoleucus). Journal of Comparative Psychology 99(2): 150-159.
- Burger, J. and R.T. Zappalorti. 1986. Nest site selection by pine snakes, Pituophis melanoleucus, in the New Jersey Pine Barrens. Copeia 1986: 116-121.
- Burger, J. and R.T. Zappalorti. 1988a. Effects of incubation temperature on sex ratios in pine snakes: differential vulnerability of males and females. American Naturalist 132(4): 492-505.
- Burger, J. and R.T. Zappalorti. 1988b. Habitat use in free-ranging pine snakes, Pituophis melanoleucus, in New Jersey Pine Barrens. Herpetologica 44:48-55.
- Burger, J. and R.T. Zappalorti. 1989. Habitat use by pine snakes (Pituophis melanoleucus) in the New Jersey Pine Barrens: individual and sexual variation. Journal of Herpetology 23:68-73.
- Burger, J. and R.T. Zappalorti. 1991. Nesting behavior of pine snakes (Pituophis m. melanoleucus) in the New Jersey Pine Barrens. Journal of Herpetology 25:152-160.
- Burger, J. and R.T. Zappalorti. 1992. Philopatry and nesting phenology of pine snakes Pituophis melanoleucus in the New Jersey Pine Barrens. Behavioral Ecology and Sociobiology 30:331-336.
- Burger, J., R.T. Zappalorti, and M. Gochfeld. 1987. Developmental effects of incubation temperature on hatchling pine snakes Pituophis melanoleucus. Comparative Biochemistry and Physiology A 87(3): 727-732.
- Burger, J., R.T. Zappalorti, J. Dowdell, T. Georgiadis, J. Hill, and M. Gochfeld. 1992. Subterranean predation on pine snakes (Pituophis melanoleucus). Journal of Herpetology 26(3): 259-263.
- Burger, J., R.T. Zappalorti, M. Gochfeld, W.I. Boarman, M. Caffrey, V. Doig, S.D. Garber, B. Lauro, M. Mikovsky. 1988. Hibernacula and summer den sites of pine snakes (Pituophis melanoleucus) in the New Jersey pine barrens. Journal of Herpetology 22(4): 425-433.
- Burger, J., W. Boarman, L. Kurzava, and M. Gochfeld. 1991. Effect of experience with pine (Pituophis melanoleucus) and king (Lampropeltis getulus) snake odors on Y-maze behavior of pine snake hatchlings. Journal of Chemical Ecology 17(1): 79-88.
- Burken, R.R., P.W. Wertz, and D.T. Downing. 1985. The effect of lipids on transepidermal water permeation in snakes. Comparative Biochemistry and Physiology A 81(2): 213-216.
- Burns, G., A. Ramos, and A. Muchlinski. 1996. Fever response in North American snakes. Journal of Herpetology 30(2): 133-139.
- Butts, T.W. 1997. Mountain Inc. wildlife monitoring Bull Mountains Mine No. 1, 1996. Western Technology and Engineering. Helena, MT.
- Carlsen, T. and R. Northrup. 1992. Canyon Ferry Wildlife Management Area Final Draft Management Plan. March 1992.
- Carpenter, C.C. 1982. The bullsnake as an excavator. Journal of Herpetology 16(4): 394-401.
- Carter, R. 1982. An observation on feeding a captive bullsnake. Bulletin of the Chicago Herpetological Society 17(4): 101.
- Cavitt, J.F. 2000. Tallgrass prairie snake assemblage food habits. Herpetological Review 31(1): 47-48.
- Chapman, G. 1995. The black pine snake, Pituophis melanoleucus lodingi; captive breeding and subsequent health problems. Herptological Review 20(1): 41-44.
- Chiszar, D. and H.M. Smith. 1993e. Pituophis catenifer sayi (bullsnake). Herpetological Review 24(4): 156.
- Chiszar, D., C. Castro, J.B. Murphy, and H.M. Smith. 1989. Discriminations between thermally different rodent carcasses by bull snakes (Pituophis melanoleucus) and cobras (Naja pallida and Aspidelaps scutatus). Bulletin of the Chicago Herpetological Society 24(10): 181-183.
- Chiszar, D., V. Lipetz, K. Scudder, and E. Pasanello. 1980. Rate of tongue flicking by bull snakes and pine snakes (Pituophis melanoleucus) during exposure to food and non-food odors. Herpetologica 36(3): 225-231.
- Cliburn, J.W. 1975. The hemipenis of pituophis melanoleucus. Journal of Herpetology 9(2): 254-255.
- Cliburn, J.W. 1976. Observations of ecdysis in the black pine snake, pituophis melanoleucus lodingi (reptilia, serpentes, colubridae). Journal of Herpetology 10(4): 299-301.
- Conners, J.S. 1986. A captive breeding of the great basin gopher snake, Pituophis melanoleucus deserticola. Herpetological Review 17(1): 12-13.
- Cooper, J. G. 1869. Notes on the fauna of the Upper Missouri. American Naturalist 3(6):294-299.
- Cooper, J. G. 1869. The fauna of Montana Territory (concluded) III. Reptiles, IV Fish. American Naturalist 3(3):124-127
- Cooper, S.V., C. Jean, and P. Hendricks. 2001. Biological survey of a prairie landscape in Montana's glaciated plains. Report to the Bureau of Land Management. Montana Natural Heritage Program, Helena, MT. 24 pp. plus appendices.
- Cope, E.D. 1900. The crocodilians, lizards, and snakes of North America. Report of the U.S. National Museum 1898: 153-1270.
- Coss, R.G. 1993. Evolutionary persistence of ground squirrel antisnake behavior: reflections on Burton's commentary. Ecological Psychology 5(2): 171-194.
- Coss, R.G. and J.E. Biardi. 1997. Individual variation in the antisnake behavior of California ground squirrels (Spermophilus beecheyi). Journal of Mammalogy 78(2): 294-310.
- Coues, E. and H. Yarrow. 1878. Notes on the herpetology of Dakota and Montana. Bulletin of the U.S. Geological Geographic Survey of the Territories 4: 259-291.
- Cross, R.G., K.L. Guse, N.S. Poran, and D.G. Smith. 1993. Development of antisnake defenses in California ground squirrels (Spermophilus beecheyi): II. Microevolutionary effects of relaxed selection from rattlesnakes. Behaviour 124(1-2): 137-164.
- Crother, B.I. (ed.) 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico. SSAR Herpetological Circular No. 37:1-84.
- Daszak, P. and A. Cunningham. 1995. A report of intestinal sarcocystosis in the bullsnake (Pituophis melanoleucus sayi) and a re-evaluation of Sarcocystis sp. from snakes of the genus Pituophis. Journal of Wildlife Diseases 31(3): 400-403.
- Day, D. 1989. Montco Terrestrial Wildlife Monitoring Report. Unpublished report for Montco, Billings, Montana.
- Day, D., P.J. Farmer, and C.E. Farmer. 1989. Montco terrestrial wildlife monitoring report December, 1987 - July, 1989. Montco, Billings, MT, and Western Technology and Engineering, Inc. Helena, MT.
- de Queiroz, A. 1984. Effects of prey type on the prey handling behavior of the bullsnake, Pituophis melanoleucus. Journal of Herpetology 18: 333-336.
- Deeming, D.C. 1989. The residues in the eggs of squamate reptiles at hatching. Herpetological Journal 1(9): 381-385.
- Diani, A.R. 1974. A comparative study of the ophidian digestive tract. Ph.D. Thesis, Saint Louis University 269p. 1974.
- Dill, C.D. 1972. Reptilian core temperatures: variation within individuals. Copeia 1972(3): 577-579.
- Diller, L.V. and D.R. Johnson. 1988. Food habits, consumption rates, and predation rates of western rattlesnakes and gopher snakes in southwestern Idaho. Herpetologica 44(2): 228-233.
- Donsworth, D. 1993. A record of keeping and successfully breeding from the northern pine snake, Pituophis melanoleucus melanoleucus, during the season 1992-1993. Herptological Review 18(3): 113-117.
- Dood, A.R. 1980. Terry Badlands nongame survey and inventory final report. Montana Department of Fish, Wildlife, and Parks and Bureau of Land Management, Helena, MT. 70 pp.
- Eakle, W.L. and T.G. Grubb. 1986. Prey remains from golden eagle nests in central Arizona. Western Birds 17(2): 87-89.
- ECON, Inc. (Ecological Consulting Service), Helena, MT., 1976, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1976. Proj. 135-85-A. December 31, 1976.
- ECON, Inc. (Ecological Consulting Service), Helena, MT., 1977, Colstrip 10 x 20 Area wildlife and wildlife habitat annual monitoring report, 1977. Proj. 164-85-A. December 31, 1977.
- ECON, Inc. (Ecological Consulting Service), Helena, MT., 1979, Annual wildllife report of the Colstrip Area for 1978. Proj. 195-85-A. April 6, 1979.
- ECON, Inc. (Ecological Consulting Service), Helena, MT., 1979, Annual wildllife report of the Colstrip Area for 1979, including a special raptor research study. Proj. 216-85-A. March 1, 1980.
- Econ, Inc. 1988. Wildlife monitoring report, 1987 field season, Big Sky Mine. March 1988. In Peabody Mining and Reclamation Plan Big Sky Mine Area B. Vol. 8, cont., Tab 10 - Wildlife Resources. Appendix 10-1, 1987 Annual Wildlife Report.
- Econ, Inc., Helena, MT., 1978, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife and wildlife habitat monitoring study. Proj. 190-85-A. December 31, 1978.
- Eichholz, M.W. and W.D. Koenig. 1992. Gopher snake attraction to birds' nests. Southwestern Naturalist 37: 293-298.
- Elmore, F.H. 1954. Gopher snake vs. ground squirrel. Yellowstone Nature Notes 28(3): 35-36.
- Engeman, R.M. and J.J. Delutes, III. 1994. Pituophis melanoleucus deserticola (great basin gopher snake). Behavior. Herpetological Review 25(3): 125.
- Ervin, S. and C. Rose. 1973. Gopher snake predation on the common bushtit. Auk 90(3): 682-683.
- Farmer, P. 1980. Terrestrial wildlife monitoring study, Pearl area, Montana June, 1978 - May, 1980. Western Technology and Engineering, Inc. Helena, MT.
- Farmer, P. J. 1980. Terrestrial Wildlife Monitoring Study, Pearl Area, Montana, June, 1978 - May, 1980. Tech. Rep. by WESTECH for Shell Oil Co.
- Fitch, H.S. 2003b. Reproduction in snakes of the Fitch Natural History Reservation in northeastern Kansas. Journal of Kansas Herpetology 6:21-24.
- Fjell, Alan K., 1986, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1985 field season. March 1986.
- Fjell, Alan K., and Brian R. Mahan, compilers., 1984, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1983 field season. February 1984.
- Fjell, Alan K., and Brian R. Mahan., 1983, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1982 field season. May 1983.
- Fjell, Alan K., and Brian R. Mahan., 1985, Peabody Coal Company Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1984 field season. February 1985.
- Fjell, Alan K., and Brian R. Mahan., 1987, Big Sky Mine, Rosebud County, MT. Wildlife monitoring report: 1986 field season. April 1987.
- Flath, D.L. 2002. Reptile and amphibian surveys in the Madison-Missouri River Corridor, Montana. Annual Progress Report. 14pp.
- Francis, A.M., J.P. Hailman, and G.E. Woolfenden. 1989. Mobbing by Florida scrub jays: behaviour, sexual asymmetry, role of helpers and ontogeny. Animal Behaviour 38(5): 795-816.
- Franz, R. 1992. Florida pine snake, Pituophis melanoleucus mugitus barbour. Rare and Endangered Biota of Florida: Amphibians and Reptiles. Paul E. Moler, editor.; Vol. III. p. 254-258.
- Frier, J.A. and R.T. Zappalorti. 1983. Reptile and amphibian management techniques. Transactons of the Northeast Fish and Wildlife Conference 40:142-148.
- Galen, C. and C. Bohn. 1979. Gopher snake preys on western big-eared bat. Murrelet 60(1): 27-28.
- Gates, M.T. 2005. Amphibian and reptile baseline survey: CX field study area Bighorn County, Montana. Report to Billings and Miles City Field Offices of Bureau of Land Management. Maxim Technologies, Billings, MT. 28pp + Appendices.
- Glup, S.S. and L.L. McDaniel. 1988. Bullsnake predation on waterfowl nests on Valentine National Wildlife Refuge, Nebraska. U.S. Forest Service General Technical Report RM 154:149-152.
- Godshalk, C.P., D.M. MacCoy, J.S. Patterson, and B.C. McKiernan. 1986. Gastric hypertrophy associated with cryptosporidiosis in a snake. Journal of the American Veterinary Medical Association 189(9): 1126-1128.
- Godwin, J.C. and P.N. Lahanas. 1984. Pituophis melanoleucus (pine snake). Herpetological Review 15(1): 21.
- Goldberg, S.R. and W.S. Parker. 1975. Seasonal testicular histology of the Colubrid snakes, Masticophis taeniatus and Pituophis melanoleucus. Herpetologica 31(3): 317-322.
- Goldthwaite, R.O. 1989. Ground squirrel antipredator behavior: time, chance and divergence. Ph.D. Dissertation, University of California (Davis); 111p.
- Goldthwaite, R.O., R.G. Coss, and D.H. Owings. 1990. Evolutionary dissipation of an antisnake system: differential behavior by California and arctic ground squirrels in above- and below-ground contexts. Behaviour 112(3/4): 246-269.
- Gomez, L.M., K.W. Larsen, and P. Walton. 2004. 'Snake Talks' in the classroom: Do they influence children's attitudes? Herpetological Review 35(4):338-341.
- Graczyk, T.K., R. Owens, and M.R. Cranfield. 1996. Diagnosis of subclinical cryptosporidiosis in captive snakes based on stomach lavage and cloacal sampling. Veterinarian Parasitology 67(3,4): 143-151.
- Greenwald, O.E. 1971a. The effect of body temperature on oxygen consumption and heart rate in the Sonora gopher snake, Pituophis catenifer affinis hallowell. Copeia 1971(1): 98-106.
- Greenwald, O.E. 1971b. The effect of temperature on the oxygenation of gopher snake blood. Comparative Biochemistry and Physiology 40A: 865-870.
- Greenwald, O.E. 1974. Thermal dependence of striking and prey capture by gopher snakes. Copeia 1974(1): 141-148.
- Greenwald, O.E. 1978. Kinematics and time relations of prey capture by gopher snakes. Copeia 1978(2): 263-268.
- Grismer, L.L. 1997. The distribution of Pituophis melanoleucus and P. vertebralis in northern Baja California, Mexico. Herpetological Review 28:68-70.
- Grismer, L.L. 2001. Comments on the taxonomy of gopher snakes from Baja California. Mexico: a reply to Rodriguez-Robles and de Jesus-Escobar. Herpetological Review 32: 81-82.
- Grismer, L.L. and C.R. Mahrdt. 1996. Pituophis melanoleucus annectens (San Diego gopher snake). Herpetological Review 27(1): 35.
- Grothe, S., C.R. Peterson, and C.H. Trost. 1991. Red-tailed hawk predation on snakes: the effects of weather and snake activity. Northwest Science 65(2): 70.
- Gutzke, W.H.N. and G.C. Packard. 1987. Influence of the hydric and thermal environments on eggs and hatchlings of bull snakes Pituophis melanoleucus. Physiological Zoology 60(1): 9-17.
- Gutzke, W.H.N., G.L. Paukstis, and L.L. McDaniel. 1985. Skewed sex ratios for adult and hatchling bullsnakes, Pituophis melanoleucus, in Nebraska (USA). Copeia 1985(3): 649-652.
- Hammerson, G.A. 1999. Amphibians and reptiles in Colorado. University Press of Colorado & Colorado Division of Wildlife. Denver, CO. 484 p.
- Hanauska-Brown, L., B.A. Maxell, A. Petersen, and S. Story. 2014. Diversity Monitoring in Montana 2008-2010 Final Report. Montana Fish, Wildlife & Parks. Helena, MT. 78 pp.
- Haywood, C.A. and R.W. Harris. 1971. Fight between rock squirrel and bullsnake. Texas Journal of Science 22(4): 427.
- Hendricks, P. 1997. Lee Metcalf National Wildlife Refuge preliminary amphibian and reptile investigations: 1996. Montana Natural Heritage Program, Helena, MT. 21 p.
- Hendricks, P. 1999a. Amphibian and reptile survey of the Bureau of Land Management Miles City District, Montana. Montana Natural Heritage Program, Helena, MT. 80 p.
- Hendricks, P. and J.D. Reichel. 1996a. Amphibian and reptile survey of the Bitterroot National Forest: 1995. Montana Natural Heritage Program. Helena, MT. 95 p.
- Hendricks, P. and J.D. Reichel. 1996b. Preliminary amphibian and reptile survey of the Ashland District, Custer National Forest: 1995. Montana Natural Heritage Program, Helena, MT. 79 p.
- Hendricks, P. and J.D. Reichel. 1998. Amphibian and reptile survey on Montana refuges: 1996. Montana Natural Heritage Program, Helena, MT. 19 p.
- Hennessy, D.F. 1983. Functional significance of variation in predator harassment. Ph.D. Dissertation, University of California (Davis); 119p. 1982.
- Hennessy, D.F. and D.H. Owings 1978. Snake species discrimination and the role of olfactory cues in the snake-directed behavior of the California ground squirrel. Behaviour 65(1-2): 115-124.
- Hicks, M. 1984. Some notes on the Louisiana pine snake. Northern Ohio Association Herpetological Notes 11(11): 11-12.
- Hirsch, S.M. and R.C. Bolles. 1980. Ability of prey to recognize predators. Zeitschrift Fuer Tierpsychologie 54(1): 71-84.
- Hirschkom, D. 1987. Pituophis melanoleucus catenifer - Pacific gopher snake. Litteratura Serpentium English Edition 7(1): 47.
- Hirschkorn, D. 1986a. Breeding results. Pituophis melanoleucus annectans. Litteratura Serpentium English Edition 6(4): 158-159.
- Hirschkorn, D. 1986b. Erfahrungen bei der Pflege und Zucht der Selten gehaltenen Bullennatter Pituophis melanoleucus catenifer. Herpetofauna (Weinstadt) 8 No. 43: 13-16.
- Horstman, G. 1995. Pituophis catenifer deserticola (Great Basin gopher snake). Herpetological Review 26(1): 47.
- Howard, W.E. 1949. Gopher snakes killed trying to swallow cottontail. Copeia 1949: 289.
- Howitz, J.L. 1986. Bull snake predation on black-capped chickadee nest. Loon 58(3): 132.
- Huey, R.B. and R.D. Stevenson. 1979. Integrating thermal physiology and ecology of ectotherms: a discussion of approaches. American Zoologist 19(1): 357-366.
- Humphris, Michael., 1993, Wildlife Monitoring Report. Spring Creek Coal Company 1993 Mining Annual Report. Appendix I. April 11, 1993.
- Humphris, Michael., 1994, Wildlife Monitoring Report. Spring Creek Coal Company 1994 Mining Annual Report. Appendix I. April 1994.
- Imler, R. 1939 and 1940. Waterfowl nesting studies and experimental bullsnake control, Crescent Lake Refuge, Nebraska, and LaCreek Refuge, South Dakota. Unpublished Report, U.S. Fish and Wildlife Service (Biological Survey).
- Imler, R.H. 1945. Bullsnakes and their control on a Nebraska Wildlife Refuge. Journal of Wildlife Management 9(4): 265-273.
- Iverson, J.B. 1990. Sex ratios in snakes: a cautionary note. Copeia 1990(2): 571-573.
- Jacobson, E.R., W. Ferris, J.T. Bagnara, W.O. Iverson. 1989. Chromatophoromas in a pine snake. Pigment Cell Research 2(1): 26-33.
- Jennings, M.R., G.B. Rathbun, and C.A. Langtimm. 1996. Pituophis melanoleucus catenifer (Pacific gopher snake). Prey. Herpetological Review 27(1): 26.
- Joslin, Gayle, and Heidi B. Youmans. 1999. Effects of recreation on Rocky Mountain wildlife: a review for Montana. [Montana]: Montana Chapter of the Wildlife Society.
- Kapfer, J.M. and C.T. Benell. 2005. Pituophis catenifer sayi (Bullsnake). Predation. Herpetological Review 36:326.
- Kennard, C. 1980. Intraspecific hybridization between a female northern pike snake and male San Diego gopher snake. Bulletin of the Philadelphia Herpetological Society 28: 3-5.
- Kingery, H.E. and U.C. Kingery. 1995. Gopher snake as predator at long-billed curlew and rough-winged swallow nests. Colorado Field Ornithology Journal 29(1): 18-19.
- Kirschkom, D. 1986. Breeding results. Pituophis melanoleucus catenifer. Litteratura Serpentium English Edition 6(4): 157-158.
- Kissner, K.J. and J. Nicholson. 2003. Bullsnakes (Pituophis catenifer sayi) in AlbertaL literature review and data compilation. Alberta Species at Risk Report 62: 1-20.
- Klauber, L.M. 1946. The gopher snakes of Baja California, with descriptions of new subspecies of Pituophis catenifer. Transactions of the San Diego Society of Natural History 11: 1-40.
- Klauber, L.M. 1947. Classification and ranges of the gopher snakes of the genus Pituophis in the western United States. Bulletin of the Zoological Society of San Diego. 22: 1-81.
- Kneeland, M.C., J.L. Koprowski, and M.C. Corse. 1995. Potential predators of Chiricahua fox squirrels (Sciurus nayaritensis chiricahuae). Southwestern Naturalist 40(3): 340-342.
- Knight, J.L. 1986. Variation in snout morphology in the North American snake (Pituophis melanoleucus) (Serpentes; Colubridae). Journal of Herpetology 20(1): 77-79.
- Koch, E.D. and C.R. Peterson. 1989. A preliminary survey of the distribution of amphibians and reptiles in Yellowstone National Park. pp. 47-49. In: Rare, sensitive and threatened species of the Greater Yellowstone Ecosystem, T.W. Clark, A.H. Harvey, R.D. Dorn, D.C. Genter, and C. Groves (eds.), Northern Rockies Conservation Cooperative , Montana Natural Heritage Program, The Nature Conservancy, and Mountain West Environmental Services. 153 p.
- Koch, E.D. and C.R. Peterson. 1995. Amphibians and reptiles of Yellowstone and Grand Teton national parks. University of Utah Press, Salt Lake City, UT. 188 p.
- Landreth, H.F. 1972. Physiological responses of Elaphe obsoleta and Pituophis melanoleucus to lowered ambient temperatures. Herpetologica 28(4): 376-380.
- Leonard, W.P. and E. Phenix. 1994. Pituophis melanoleucus (gopher snake). Herpetological Review 25(4): 168.
- Licht, P. and A.F. Bennett. 1972. A scaleless snake: tests of the role of reptilian scales in water loss and heat transfer. Copeia 1972(4): 702-707.
- Lilley, T. 1985. Albinism in snakes. Freshwater and Marine Aquarium 8(10): 68-69.
- Lillywhite, H.B. 1985a. Postural edema and blood pooling in snakes. Physiological Zoology 58(6): 759-766.
- Lipetz, V. 1977. Behavior of bull snakes during prolonged exposure to food and other odors. Journal of the Colorado-Wyoming Academy of Science 9(1): 2.
- Loughry, W.J. 1987. Differences in experimental and natural encounters of black-tailed prairie dogs with snakes. Animal Behaviour 35(5): 1568-1570.
- Mader, D.R., C.C. Horvath, and J. Paul-Murphy. 1985. The hematocrit and serum profile of the gopher snake (Pituophis melanoleucas catenifer). Journal of Zoo Animal Medicine 16(4): 139-140.
- Marr, N.V. 1985. Gopher snake preys on northern oriole nestlings. Murrelet 66(3): 95-97.
- Martin, P.R. 1980a. Terrestrial wildlife habitat inventory in southeastern Montana. Montana Department of Fish, Wildlife and Parks and Bureau of Land Management, Helena MT. 114 p.
- Martin, P.R. 1980b. Terrestrial wildlife inventory in selected coal areas of Montana. Montana Department of Fish, Wildlife and Parks and Bureau of Land Management, Helena, MT. 84 p.
- Martin, P.R., K. Dubois and H.B. Youmans. 1981. Terrestrial wildlife inventory in selected coal areas, Powder River resources area final report. Montana Department of Fish, Wildlife and Parks and Bureau of Land Management, Helena, MT. No. YA-553-CTO- 24. 288 p.
- Martindale, P. 1929. The bull snake at close range. Yellowstone Nature Notes 6(6): 4.
- Matthews, W.L. 1979. Wibaux-Beach wildlife baseline study - nongame species. Bureau of Land Management, Miles City, MT. 93 p.
- Matthews, W.L. 1980a. Wibaux-Beach comparison study: Sydney, Glendive and Plevna Study Areas. Bureau of Land Management, Miles City, MT. 50 p.
- Matthews, W.L. 1980b. Wildlife of Prairie County Terry study area. Bureau of Land Management, Miles City, MT. 52 p.
- Matthews, W.L. 1981. Broadus-Pumpkin Creek baseline inventory - wildlife. Bureau of Land Management, Miles City, MT. 83 p.
- Matthews, W.L. 1982. Bloomfield-North Fork Baseline Inventories - Wildlife. Unpublished report to the Bureau of Land Management, Miles City, Montana. 61 pp.
- Maxell, B.A. 2016. Northern Goshawk surveys on the Beartooth, Ashland, and Sioux Districts of the Custer-Gallatin National Forest: 2012-2014. Montana Natural Heritage Program. Helena, MT. 114pp.
- Maxell, B.A., J.K. Werner, P. Hendricks, and D.L. Flath. 2003. Herpetology in Montana: a history, status summary, checklists, dichotomous keys, accounts for native, potentially native, and exotic species, and indexed bibliography. Society for Northwestern Vertebrate Biology, Northwest Fauna Number 5. Olympia, WA. 135 p.
- Maxson, G.A.D. 1981. Arboreal nest predation by a bullsnake. Loon 53(1): 61-62.
- McAllister, C.T. 1984. Pituophis melanoleucus sayi (bullsnake). Herpetological Review 15(3): 78.
- McDonald, M.G. 1981. Terrestrial Wildlife Inventory, Redwater Project Area. Unpublished report for WESCO Resources, Inc., Billings, Montana.
- McEneaney, T. and J. Jensen. 1974. The reptiles and amphibians of the Charles M. Russell National Wildlife Range - 1974. Charles M. Russell National Wildlife Refuge. Lewistown, MT. 3 p.
- Merli, J. 1992. Nesting habits of the northern pine snake (Pituophis m. melanoleucus). Vivarium 4(1): 16-19.
- Miller, J.E. and B.D. Leopold. 1992. Population influences: Predators. In James G. Dickson, ed. The wild turkey: Biology and management, p.119-128. Stackpole Books, Harrisburg, Pennsylvania.; References cited,
- Mitchell, J.C. and C.A. Pague. 1987. A review of reptiles of special concern in Virginia. Virginia Journal of Science 38(2): 84.
- Moon, B.R. 2000. The mechanics of swallowing and the muscular control of diverse behaviours in gopher snakes. The Journal of Experimental Biology 203: 2589-2601.
- Moriarty, J. 1991. Reintroduction of bullsnakes into the Crow-Hassan prairie restoration. Final report submitted to Nongame Wildlife Program, Minnesota Department of Natural Resources. 6 pp.
- Morris, M.A. 1986. Anesthesia of snakes (Pituophis melanoleucus and Python regius) fed ether-killed rats. Herpetological Review 17(4): 88.
- Mount, R.H. 1986a. Black pine snake. Pp. 35-36. In: Mount, R.H. [Ed.] Vertebrate animals of Alabama in need of special attention. Alabama Agricultural Experiment Station, Auburn, Alabama.
- Mount, R.H. 1986c. Northern pine snake. pp. 70-71. In: Mount, R.H. [Ed.] Vertebrate animals of Alabama in need of special attention. Alabama Agricultural Experiment Station, Auburn, Alabama. 1986
- Mundinger, J.G. 1975. The influence of rest-rotation grazing management on waterfowl production on stock-water reservoirs in Phillips County, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 100 p.
- Newlon, K.R. 2005. Demography of Lewis's Woodpecker, breeding bird densities, and riparian Aspen integrity in a grazed landscape. M.Sc. Thesis. Bozeman, MT: Montana State University. 101 p.
- Niedrach, R.J. 1971. Bull snake and common grackles. Wilson Bulletin 83: 317-318.
- OEA Research. 1985. Wildlife Inventory:Monitoring Report for the CX Ranch Project. 1983-1984. Unpublished report for Consolidation Coal Company, Pittsburgh, Pennsylvania.
- Oechsli, L.M. 2000. Ex-urban development in the Rocky Mountain West: consequences for native vegetation, wildlife diversity, and land-use planning in Big Sky, Montana. M.Sc. Thesis. Montana State University, Bozeman. 73 p.
- Ohlendorf, H.M., R.L. Hothem, and T.W. Aldrich. 1988. Bioaccumulation of selenium by snakes and frogs in the San Joaquin Valley, California (USA). Copeia 1988(3): 704-710.
- Olsen, U. 1986. North American reptiles 2. Bullsnake - in nature and in the vivarium. Nordisk Herpetologisk Forening 29(4): 90-106.
- Olson, R.E. 1995. Important herpetological notes for northern Illinois and southern Wisconsin. Bulletin of the Maryland Herpetological Society 31(2): 96.
- Owings, D.H. and W.J. Loughry. 1985. Variation in snake-elicited jump-yipping by black-tailed prairie dogs: ontogeny and snake-specificity. Zeitschrift Fuer Tierpsychologie 70(3): 177-200.
- Pack, H.J. 1919. Note on food habits of the bull snake. Copeia 68: 16.
- Packard, M.J. and G.C. Packard. 1988. Sources of calcium and phosphorus during embryogenesis in bullsnakes (Pituophis melanoleucus). Journal of Experimental Zoology 246(2): 132-138.
- Palmer, A.C. 1985. Second generation intraspecific hybrids of Pituophis melanoleucus. Bulletin of the Chicago Herpetological Society 20(1): 21-22.
- Parker, W.S. 1974. Comparative ecology of two colubrid snakes, Masticophis t. taeniatus (hallowell) and Pituophis melanoleucus deserticola stejneger, in northern Utah. Ph.D. Thesis, University of Utah 307p. 1974.
- Patla, D.A. and C.R. Peterson. 1997. Amphibians and reptiles along the Grand Loop Highway in Yellowstone National Park: Mammoth Hot Springs to Norris Junction. 1 February, 1997. Greater Yellowstone Ecosystem Amphibian Survey and Monitoring Program, Herpetology Laboratory, Department of Biological Sciences, Idaho State University, Pocatello, ID. 60 p.
- Peabody, F.E. 1958. A Kansas drought recorded in growth zones of a bullsnake. Copeia 1958: 91-94.
- Peery, T.E. 1932. Miscellaneous note on a bull snake. Yellowstone Nature Notes 9(6-7): 31.
- Perez-Higareda, G. 1981. The occurrence of Pituophis melanoleucus sayi in Veracruz (serpentes: colubridae). Bulletin of the Maryland Herpetological Society 17(2): 64-67.
- Peterson, C.R. and J.P. Shive. 2002. Herpetological survey of southcentral Idaho. Idaho Bureau of Land Management Technical Bulletin 02-3:1-97.
- Pfaffenberger, G.S., N.M. Jorgensen, and D.D. Woody. 1989. Parasites of prairie rattlesnakes (Crotalus viridis viridis) and gopher snakes (Pituophis melanoleucus sayi) from the eastern high plains of New Mexico (USA). Journal of Wildlife Diseases 25(2): 305-306.
- Pilliod, D.S. and T.C. Esque. 2023. Amphibians and reptiles. pp. 861-895. In: L.B. McNew, D.K. Dahlgren, and J.L. Beck (eds). Rangeland wildlife ecology and conservation. Cham, Switzerland: Springer. 1023 p.
- Platt, D.R. 1984. Growth of bullsnakes (Pituophis melanoleucus sayi) on a sand prairie in south central Kansas. Vertebrate Ecology and Systematics. Richard A. Seigel, Lawrence E. Hunt, James L. Knight, Luis Malaret, and Nancy L. Zuschlag, editors; p. 41-56.
- Poran, N.S. and R.G. Coss. 1990. Development of antisnake defenses in California ground squirrels (Spermophilus beecheyi): I. behavioral and immunological relationships. Behaviour 112(3-4): 222-245.
- Powder River Eagle Studies, Gillette, WY., 1992, Big Sky Mine 1991 wildlife monitoring studies. Rev. February 1992.
- Powder River Eagle Studies, Inc., Gillette, WY., 1993, Big Sky Mine 1992 wildlife monitoring. Rev. February 1993.
- Powder River Eagle Studies, Inc., Gillette, WY., 1996, Spring Creek Mine 1995 Wildlife Monitoring Studies. Spring Creek Coal Company 1995-1996 Mining Annual Report. Vol. I, App. I. May 1996.
- Powder River Eagle Studies, Inc., Gillette, WY., 1999, Spring Creek Mine 1998 Wildlife Monitoring. March 1999.
- Powder River Eagle Studies, Inc., Gillette, WY., 2000, Spring Creek Mine 1999 Wildlife Monitoring. March 2000.
- Raiti, P. 1993. Occult coccidiosis in a bullsnake, Pituophis melanoleucus ssp. Bulletin of the Association of Amphibian and Reptilian Veterinarians 3(1): 5-6.
- Ramirez, B.A., M.A. Gutierrez, and R.A. Gonsalez. 1995. Clutch Sizes in a Community of Snakes from the Mountains of the Valley of Mexico. Herpetological Review 26(1): 12-13.
- Randall, J.A., S.M. Hatch, and E.R. Hekkala. 1995. Inter-specific variation in anti-predator behavior in sympatric species of kangaroo rat. Behavioral Ecology and Sociobiology 36(4): 243-250.
- Rauscher, R.L. 1998. Amphibian and reptile survey on selected Montana Bureau of Reclamation impoundments. Montana Department of Fish, Wildlife and Parks, Nongame Program. Bozeman, MT. 24 pp.
- Rauscher, R.L. 2000. Amphibian and reptile survey on selected Montana Bureau of Reclamation impoundments. Unpublished report, Montana Fish, Wildlife & Parks Non-game Program. 12 pp + maps, tables.
- Redmond, R.L. and D.A. Jenni. 1986. Population ecology of the Long-billed curlew (Numenius americanus) in western Idaho. The Auk 103(4):755-767.
- Reichel, J. and D. Flath. 1995. Identification of Montana's amphibians and reptiles. Montana Outdoors 26(3):15-34.
- Reichel, J. D. In prep. Amphibian and reptile survey in southwest Montana: 1996. Unpublished report.
- Reichel, J.D. 1995b. Preliminary amphibian and reptile survey of the Sioux District of the Custer National Forest: 1994. Montana Natural Heritage Program, Helena, MT. 75 p.
- Reichel, J.D. 1997a. Amphibian, reptile and northern bog lemming survey on the Rocky Mountain Front: 1996. Montana Natural Heritage Program, Helena, MT. 81 p.
- Reichling, S.B. 1988. Reproduction in captive Louisiana pine snakes, Pituophis melanoleucus ruthveni. Herpetological Review 19(4): 77-78.
- Reichling, S.B. 1990. Reproductive traits of the Louisiana pine snake Pituophis melanoleucus ruthveni (Serpentes: Colubridae). Southwestern Naturalist 35(2): 221-222.
- Reichling, S.B. 1995. The taxonomic status of the Louisiana pine snake (Pituophis melanoleucus ruthveni) and its relevance to the evolutionary species concept. Journal of Herpetology 29(2): 186-198.
- Robbins, A.C. 1991. Anatomy drawing of a nonpoisonous (gopher) snake. Bulletin of the Chicago Herpetological Society 26(5): 110.
- Roberts, C. 1991. Notes on the captive breeding, care and hibernation of the northern pine snake, Pituophis melanoleucus melanoleucus. Herptological Review 16(2): 68-69.
- Rodgers, T. L. and W. L. Jellison. 1942. A collection of amphibians and reptiles from western Montana. Copeia (1):10-13.
- Rodríguez-Robles, J.A. 1998. Alternative perspectives on the diet of gopher snakes (Pituophis catenifer, Colubridae): literature records versus stomach contents of wild and museum specimens. Copeia 1998: 463-466.
- Rodriguez-Robles, J.A. 2002. Feeding ecology of the North American gopher snake (Pituophis catenifer, Colubridae). Biological Journal of the Linnean Society 77(2):165-183.
- Rodríguez-Robles, J.A. 2003. Home ranges of gopher snakes (Pituophis catenifer, Colubridae) in central California. Copeia 2003(2):391-396.
- Rodríguez-Robles, J.A. and J.M. De Jesus-Escobar. 2000. Molecular systematics of New World gopher, bull, and pinesnakes (Pituophis: Colubridae), a transcontinental species complex. Molecular Phylogenetics and Evolution 14(1): 35-50.
- Roedel, M.D. and P. Hendricks. 1998a. Amphibian and reptile survey on the Bureau of Land Management Lewistown District: 1995-1998. Montana Natural Heritage Program, Helena, MT. 53 p.
- Roedel, M.D. and P. Hendricks. 1998b. Amphibian and reptile inventory on the Headwaters and Dillon Resource Areas in conjunction with Red Rocks Lakes National Wildlife Refuge: 1996-1998. Montana Natural Heritage Program, Helena, MT. 46 p.
- Roth, J.J. and H.M. Smith. 1990a. Pituophis melanoleucus deserticola (Great Basin gopher snake). Herpetological Review 21(2): 41.
- Russell, A. P. and A. M. Bauer. 1993. The amphibians and reptiles of Alberta. University of Calgary Press. Calgary, Alberta. 264 p.
- Schroder, R.C. 1950. Hibernation of blue racers and bull snakes in western Illinois. Chicago Academy of Science and Natural History Miscellaneous 75: 1-2.
- Scow, K.L. 1980. Terrestrial wildlife survey American Colloid study area Phillips County, Montana. Western Technology and Engineering, Inc., Helena, MT.
- Skinner, M.P. 1924. The Yellowstone Nature Book. A.C. McClurg Company, Chicago, IL. 221 p.
- Smith, G.R. and J.B. Iverson. 1993. Reactions to odor trails in bullsnakes. Journal of Herpetology 27(3): 333-335.
- Smith, H.M. and D. Thompson. 1993. Four reptiles newly recorded from Ouray County, Colorado. Bulletin of the Chicago Herpetological Society 28(4): 78-79.
- Smith, H.M. and J.P. Kennedy. 1951. Pituophis melanoleucus ruthveni in eastern Texas and its bearing on the status of Pituophis catenifer. Herpetologica 7: 93-96.
- Speake, D.W. 1986. Florida pine snake. pp. 36-37. In: Mount, R.H. [Ed.] Vertebrate animals of Alabama in need of special attention. Alabama Agricultural Experiment Station, Auburn, Alabama.
- Spring Creek Coal Company., 1992, Wildlife Monitoring Report. Spring Creek Coal Company 1992 Mining Annual Report. Appendix I.
- St. John, A.D. 2002. Reptiles of the northwest: California to Alaska, Rockies to the coast. Lone Pine Publishing, Renton, WA. 272 p.
- Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. 3rd Edition. Houghton Mifflin Company, Boston and New York. 533 p.
- Sterner, R.T., B.E. Peterson, S.A. Shumake, S.E. Gaddis, J.B. Bourassa, T.A. Felix, G.R. McCann, K.A. Crane, and A.D. Ames. 2002. Movements of a bullsnake (Pituophis catenifer) following predation of a radio-collared northern pocket gopher (Thomomys talpoides). Western North American Naturalist 62(2):240-242.
- Stevenson, D. and D. Crowe. 1992b. Pituophis melanoleucus mugitus (Florida pine snake). Herpetological Review 23(3): 92.
- Stinner, J.N. 1981. Pulmonary anatomy, gas exchange, and acid-base balance in the gopher snake, Pituophis melanoleucus catenifer. Ph.D. Dissertation, University of California (Riverside); 146p. 1980.
- Stinner, J.N. 1982. Functional anatomy of the lung of the snake Pituophis melanoleucus. American Journal of Physiology 243(3): R251-R257.
- Stinner, J.N. 1987b. Gas exchange and air flow in the lung of the snake, Pituophis melanoleucus. Journal of Comparative Physiology B Biochemical Systems Environmental Physiology 157(3): 307-314.
- Storm, R. M., and W. P. Leonard (eds.). 1995. Reptiles of Washington and Oregon. Seattle Audubon Society. Seattle, WA. 176 pp.
- Stull, O.G. 1940. Variations and relationships in the snakes of the genus Pituophis. Bulletin of the U.S. National Museum - Smithsonian Institution, Washington, D.C. 175: 1-225.
- Sullivan, B.K. 1981. Observed differences in body temperature and associated behavior of four snake species. Journal of Herpetology 15(2): 245-246.
- Sweet, S.S. 1985. Geographic variation, convergent crypsis and mimicry in gopher snakes (Pituophis melanoleucus) and western rattlesnakes (Crotalus viridis). Journal of Herpetology 19(1): 55-67.
- Sweet, S.S. and W.S. Parker. 1990. Pituophis melanoleucus (Daudin). Pine, bull, and gopher snakes. Catalogue of American Amphibians and Reptiles 474: 1-8.
- Thomas, R.A., B.J. Davis, and M.R. Culbertson. 1976. Notes on variation and range of the Louisiana pine snake, (Pituophis melanoleucus ruthveni) stull (reptilia, serpentes, colubridae). Journal of Herpetology 10(3): 252-257.
- Thompson, B.C. and C.L. Turner. 1980. Bull snake predation at a cliff swallow nest. Murrelet 61(1): 35-36.
- Thompson, L.S. 1981. Circle West wildlife monitoring study: Third annual report. Technical report No. 8. Montana Department of Natural Resources and Conservation. Helena, Montana.
- Thompson, L.S. 1982. Circle West Wildlife Monitoring Study. Fourth annual report. Technical report 10. Montana Department of Natural Resources and Conservation, Helena, Montana.
- Timken, R. No Date. Amphibians and reptiles of the Beaverhead National Forest. Western Montana College, Dillon, MT. 16 p.
- Timm, K.I., R.J. Sonn, and B.D. Hultgren. 1988. Coccidioidomycosis in a Sonoran gopher snake, Pituophis melanoleucus affinis. Journal of Medical and Veterinary Mycology 26(2): 101-104.
- Towers, S.R. and R.G. Coss. 1991. Antisnake behavior of Columbian ground squirrels (Spermophilus columbianus). Journal of Mammalogy 72(4): 776-783.
- Tucker, J.K. 1994b. Noteworthy distributional records from some snakes from Jersey and Madison Counties, Illinois. Herpetological Review 25(2): 79-80.
- Tucker, J.K. 1995. Notes on Road-Killed snakes and their implications on habitat modification due to summer flooding on the Mississippi River in West Central Illinois. Transactions of the Illinois State Academy of Science 88(1-2): 61-71.
- Turner, F.B. 1951. A checklist of the reptiles and amphibians of Yellowstone National Park with incidental notes. Yellowstone Nature Notes 25(3): 25-29.
- Turner, F.B. 1955. Reptiles and amphibians of Yellowstone National Park. Yellowstone Interpretive Series No. 5. Yellowstone Library and Museum Association. Yellowstone National Park, WY. 40 p.
- Van Denburgh, J. 1920. A further study of variation in the gopher snakes of western North America. Proceedings of the California Academy of Sciences (4), 10: 1-27.
- Van Denburgh, J. and J.R. Slevin. 1919. The gopher snakes of western North America. Proceedings of the California Academy of Sciences 9(6): 197-220.
- Van der Eerdn, H. 1989. Successful breeding of the bullsnake (Pituophis melanoleucus sayi). Litteratura Serpentium English Edition 9(3): 129-132.
- Van Devender, R.W. and P.F. Nicoletto. 1983. Lower Wilson Creek, Caldwell County, North Carolina (USA): A thermal refugium for reptiles? Brimleyana 0(9): 21-32.
- Vejersley, L.O. 1985. Breeding results: Pituophis melanoleucus catenifer. Litteratura Serpentium 5(2): 77.
- Vitt, L.J., J.P. Caldwell, and D.B. Shepard. 2005. Inventory of amphibians and reptiles in the Billings Field Office Region, Montana. Sam Noble Oklahoma Museum of Natural History and Department of Zoology, University of Oklahoma, Norman, OK. 33 pp.
- VTN Colorado, Inc. Decker Coal Company., 1975, Draft environmental impact assessment for the proposed North Extension of the West Decker Mine.
- Waage, B.C. 1998. Western Energy Company Rosebud Mine 1997 annual wildlife monitoring report December 1, 1996 to November 30, 1997 survey period. Western Energy Company, Colstrip, MT.
- Waage, Bruce C., 1996, Western Energy Company Rosebud Mine, Colstrip, Montana: 1995 Annual Wildlife Monitoring Report; December 1, 1994 - November 30, 1995. February 28, 1996.
- Waage, Bruce C., 1997, Western Energy Company Rosebud Mine, Colstrip, Montana: 1996 Annual Wildlife Monitoring Report; December 1, 1995 - November 30, 1996 Survey Period. February 28, 1997.
- Waage, Bruce C., 1998, Western Energy Company Rosebud Mine, Colstrip, Montana: 1997 Annual Wildlife Monitoring Report; December 1, 1996 - November 30, 1997 Survey Period. March 23, 1998.
- Waage, Bruce C., 1999, Western Energy Company Rosebud Mine, Colstrip, Montana: 1998 Annual Wildlife Monitoring Report; December 1, 1997 - November 30, 1998 Survey Period. February 24, 1999.
- Waage, Bruce C., 2000, Western Energy Company Rosebud Mine, Colstrip, Montana: 1999 Annual Wildlife Monitoring Report; December 1, 1998 - November 30, 1999. February 2000.
- Waage, Bruce C., 2001, Western Energy Company Rosebud Mine, Colstrip, Montana: 2000 Annual Wildlife Monitoring Report; December 1, 1999 - November 30, 2000. March 30, 2001.
- Weaver, R.E. 2004a. Pituophis catenifer (Gopher Snake). Diet. Herpetological Review 35(2):179-180.
- Weisel, G.F. 1952. Animal names, anatomical terms, and some ethnozoology of the Flathead Indians. Journal of the Washington Academy of Sciences 42(11): 345-355.
- Wellstead, C.F. 1981. Behavioral observation in bullsnakes. Herpetological Review 12(1): 6.
- Werner, J.K. and J.D. Reichel. 1994. Amphibian and reptile survey of the Kootenai National Forest: 1994. Montana Natural Heritage Program. Helena, MT. 104 p.
- Werner, J.K. and J.D. Reichel. 1996. Amphibian and reptile monitoring/survey of the Kootenai National Forest: 1995. Montana Natural Heritage Program. Helena, MT. 115 pp.
- Werner, J.K. and T. Plummer. 1995a. Amphibian and reptile survey of the Flathead Indian Reservation 1993-1994. Salish Kootenai College, Pablo, MT. 55 pp.
- Werner, J.K. and T. Plummer. 1995b. Amphibian monitoring program on the Flathead Indian Reservation 1995. Salish Kootenai College, Pablo, MT. 46 p.
- Werner, J.K., B.A. Maxell, P. Hendricks and D.L. Flath. 2004. Amphibians and Reptiles of Montana. Mountain Press Publishing Company: Missoula, MT. 262 pp.
- Werner, J.K., T. Plummer, and J. Weaslehead. 1998a. Amphibians and reptiles of the Flathead Indian Reservation. Intermountain Journal of Sciences 4(1-2): 33-49.
- West, C. 1995. Notes on the captive breeding of the northern pine snake (Pituophis melanoleucus melanoleucus). Herptological Review 20(3): 109-111.
- Western Technology & Engineering, Inc. (WESTECH)., 1991, 1991 Bull Mountains Mine No. 1 Terrestrial Wildlife Monitoring Study. In Meridian Minerals Company Bull Mountains Mine No. 1 Permit Application, Musselshell County, Montana. Vol. 7 of 14: Section 26
- Western Technology and Engineering, Inc. (WESTECH)., 1991, Wildlife Monitoring and Additional Baseline Inventory: Absaloka Mine Area Annual Report, 1991. Montana SMP 85005 R1. OSMP Montana 0007B. Febr. 25, 1991.
- Western Technology and Engineering, Inc. (WESTECH)., 1994, Wildlife Monitoring Absaloka Mine Area Annual Report, 1994. Montana SMP 85005. OSMP Montana 0007D. Febr. 24, 1994.
- Western Technology and Engineering, Inc. (WESTECH)., 1997, Wildlife Monitoring Absaloka Mine Area Annual Report, 1996. Montana SMP 85005. OSMP Montana 0007D. Mar. 1997.
- Western Technology and Engineering, Inc. (WESTECH)., 1999, Wildlife Monitoring Absaloka Mine Area Annual Report, 1998. SMP 85005. OSMP Montana 0007E. April 1999.
- Western Technology and Engineering, Inc. (WESTECH)., 2000, Wildlife Monitoring Absaloka Mine Area Annual Report, 1999. Montana SMP 85005. OSMP Montana 0007E. February 2000.
- Western Technology and Engineering, Inc. (WESTECH)., 2001, Wildlife Monitoring Absaloka Mine Area Annual Report, 2000. Montana SMP 85005. OSMP Montana 0007E. February 2001.
- Westmoreland Resources, Inc., Hardin, MT., 1981, 1981 Wildlife Report. April 1982.
- White, C.A. 1884. On the character and function of the epiglottis in the bull snake (Pityophis). American Naturalist 18: 19-21.
- Wied, M.P. 1843. Travels in the interior of North America by Maximilian, Prince of Wied. With numerous engravings on wood, and a large map. Translated from the German by H. Evans Lloyd. To accompany the original series of eighty-one elaborately-coloured plates. Size, imperial folio. Ackerman and Co., London, England. 520 p.
- Wied, M.P. 1865. Verzeichniss der reptilien, welche auf einer reise in nordlichen America beobachtet wurden, von Maximilian, Prinzen zu Wied. Eigengangen bei der Akademie am 1, Juni 1865. Druck von E. Blochmann und Sohn, Dresden, Germany. 141 p.
- Wootten, M. 1994. The northern pine snake, Pituophis melanoleucus melanoleucus, - success and failure. Herptological Review 19(1): 24-26.
- Wright, J. 1996. Variations within populations of the bullsnake. Reptile and Amphibian Magazine 42:16-22.
- Yannone, V. 1978. The bullsnake: Montana's big hisser. Montana Outdoors 10(2): 27-28.
- Yarrow, H.C. 1882. Check list of North American reptilia and batrachia, with catalogue of specimens in the U.S. National Museum. United States National Museum Bulletin 24. 249 p.
- Yeager, D.C. 1929. Reptiles of Yellowstone Park with notes on the Amphibia. Yellowstone Nature Notes. Yellowstone National Park Library, Mammoth, WY. 12 p.
- Young, B.A., S. Sheft, and W. Yost. 1995. Sound production in Pituophis melanoleucus (Serpentes: Colubridae) with the first description of a vocal cord in snakes. Journal of Experimental Zoology 273(6): 472-481.
- Young, R.A. and T.L. Vandeventer. 1988. Recent observations of the Louisiana pine snake, Pituophis melanoleucus ruthveni Stull. Bulletin of the Chicago Herpetological Society 23(1-2): 203-207.
- Zackheim, K. 1973. Exhibit H: Wildlife Study. In Ash Grove Cement Co. files.
- Additional Sources of Information Related to "Reptiles"